Slice the tomatoes in half crosswise through the middle. You will have a top and a bottom half. Place into a large bowl and toss with toasted sesame oil, the whole garlic cloves, salt, and pepper.
Roast on a parchment lined sheet pan for 30 minutes. Turn the heat down to 275°F and cook for an additional 1-2 hours depending on the size of the tomatoes. Let cool.
For the noodles
Bring a large pot of salted water to a boil. Add the udon noodles and cook until tender. Drain and rinse under cold running water to stop the cooking. Set aside.
For the broth
In a large soup pot, make the dashi (broth) by adding the kombu and water. Bring to a gentle simmer and then turn off heat. Pour the dashi through a fine sieve. Discard the kelp. Pour the dashi back into the soup pot.
Add the rest of the broth ingredients to the pot and bring to a simmer. Simmer for 15 minutes. Turn off the heat and check seasoning.
For the tofu
Heat the oil in a large skillet. Fry the tofu on both sides and set aside on paper towels to drain. Add the tofu to the broth.
Serving
Divide the noodles into 4 bowls. Ladle the hot broth mixture over the noodles and serve immediately.
If using the roasted tomatoes- pull the skin off the cooked tomatoes and add one half to the top of each bowl.